Sökning: "covers"

Visar resultat 1 - 5 av 944 avhandlingar innehållade ordet covers.

1. 1. Building Data for Stacky Covers and the Étale Cohomology Ring of an Arithmetic Curve : Du som saknar dator/datorvana kan kontakta [email protected] för information

   Författare :Eric Ahlqvist; David Professor; Niels Borne; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Étale Cohomology; Number Field; Cup Product; Stacky Covers; Building Data; Ramified Covers; Mathematics; Matematik;

   Sammanfattning : This thesis consists of two papers with somewhat different flavours. In Paper I we compute the étale cohomology ring H^*(X,Z/nZ) for X the ring of integers of a number field K. As an application, we give a non-vanishing formula for an invariant defined by Minhyong Kim. LÄS MER

3. 2. Arithmetic of three-point covers

   Författare :Björn Selander; Siegfried Bosch; Uppsala universitet; []
   Nyckelord :Algebra and geometry; Algebra och geometri;

   Sammanfattning : Any cover of the Riemann sphere with rational branch points is known to be defined over the algebraic numbers. Hence the Galois group of the rationals acts on the category of such branched covers. Particulars about this action are still scarce, even in the simplest non-abelian case, the case with just three branch points. LÄS MER

4. 3. Snarks : Generation, coverings and colourings

   Författare :Jonas Hägglund; Roland Häggkvist; Klas Markström; Luis Goddyn; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Snarks; cubic graphs; enumeration; cycle covers; perfect matching covers; Fulkerson s conjecture; strong cycle double cover conjecture; cycle decompositions; stable cycles; oddness; circumference; uncolourability measures; Mathematics; matematik;

   Sammanfattning : For a number of unsolved problems in graph theory such as the cycle double cover conjecture, Fulkerson's conjecture and Tutte's 5-flow conjecture it is sufficient to prove them for a family of graphs called snarks. Named after the mysterious creature in Lewis Carroll's poem, a \emph{snark} is a cyclically 4-edge connected 3-regular graph of girth at least 5 which cannot be properly edge coloured using three colours. LÄS MER

5. 4. Admissible covers, modular operads and modular forms

   Författare :Dan Petersen; Carel Faber; Alessandro Chiodo; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : This thesis contains three articles related to operads and moduli spaces of admissible covers of curves. In Paper A we isolate cohomology classes coming from modular forms inside a certain space of admissible covers, thereby showing that this moduli space can be used as a substitute for a Kuga–Sato variety. LÄS MER

7. 5. Thermal ice pressure in lake ice covers

   Författare :Lars Bergdahl; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : .... LÄS MER